Unit 3.8: Fractions, Decimals and Percent Lesson: Solving Percent Problems

Transcription

1 Unit 3.8: Fractions, Decimals and Percent Lesson: Solving Percent Problems Objectives: Students will learn to solve problems involving percent. These include discount questions, percentage of a number, and questions involving sales tax. Procedure: We use percentage in money a lot. Where have you seen percentage in the world of money? (answers can include discount, profit, sales tax, tips etc.) You will have to calculate the answers to all these types of questions. One of the skills we need for these types of problems is calculating the percentage of a number. For example what is 30% of 155, or what is 20% of 45. To calculate this, we need to change the percent into its equivalent decimal form and multiply. (note the word of usually means to multiply in word problems) What is 30% of 56? Convert 30 percent into a decimal. Now multiply 0.3 by 56, this gives So 30% of 56 is. What is 82% of 287? Convert 82% to decimal equivalent and multiply by 287. So 82% of 287 is 1

2 You try one: What is 75% of 21? So now lets use this in a typical problem you may see in shopping. Discount: Discount is the amount that a price is. It is usually given as a percentage off the regular price. For example 25% off or 30% off. A typical question reads like the following: A coat is on sale for 30% off. If the regular price is $85.00, what is the discount and the new price. What is the Discount? To calculate the discount of 30% off $85.00, you need to find 30% of 85. To do this, convert 30% to its decimal equivalent and multiply. (Note that the word of means to multiply in most cases. What is 30% in its equivalent decimal form? Now multiply 0.3 by 85. Remember that we are working in dollars, so this is a discount of $. 2

3 What is the new price? New price=regular price discount New price = New price = A used car is on sale for 15% off. If the regular price is $3000, what is the discount and the new price? Discount: So the discount is $. Sales Price New price = New price = The new price is 3

4 A calculator is on regularly priced at $17.49, the store places the calculator on sale for 40% off. What is the new price? Discount Round the discount to the nearest penny gives. New price = = $10.49 Can you think of another method of doing this problem? 4

5 Taxes Taxes are an extra amount we pay to help fund the services we use. Things like roads, fire department, police, healthcare, hospitals, schools etc. The money has to come from somewhere, so people in our country pay taxes to help pay for these things. In Alberta we have one single tax called the Goods and Services Tax, which we refer to as the GST. This GST used to be 7%, but it was reduced to 5%. In other provinces there is also another tax called the provincial sales tax. The province sets these taxes. All taxes are added to the price of the item you pay for. For example, if you pay $1.00 for a taxable item in the store, the store adds 5% or 5 cents to the price, so you pay $1.05, for an item priced at $1.00. A desk is sold at Office Depot for $450. What is the GST and the total price to the consumer (buyer)? GST GST is 5% of the items cost. So the GST is $. What is the total cost? Total cost = + Total cost = + Total cost = $ 5

6 A freezer is priced at $ What is the GST and the total cost to the buyer? Rounding to the nearest cent gives a GST of $ Total cost + = Tide detergent is priced at $3.99. What is the tax on this item? The tax is $ Lets combine both discount and sales tax now: 6

7 On a shopping trip Mrs. Edey sees a new computer on sale for $ The computer is on sale for 30% off. If she buys the computer what will she pay including GST? Discount: New Price: GST Total cost: The cost including GST for the computer is. 7

8 Complete Page 115 #1-8 HWB Page Unit Review: Page 121#1-18 HWB Page Practice Test Page 123 Cumulative Review Page Unit 3 Final Exam 8